Music Streaming Wars: Top 8 Contenders

iTunes Radio

Google Music Play All Access

Spotify

Pandora

Rdio

Piki

Grooveshark

Songza

It's official: Apple is in the streaming music business. The company unveiled its much-anticipated streaming music service Monday at its Worldwide Developers Conference in San Francisco.

Dubbed iTunes Radio, the service debuts this fall. It's likely to be a game-changer in a crowded industry that thus far has crowned no clear winner.

Here's a look at the leading contenders vying to win the streaming wars.--Jill Krasny

Background: Despite entering a crowded space, iTunes Radio could take online radio mainstream, much like iTunes did with digital music.

Specs: Free, but iTunes Radio will be ad-supported, so users will have to pony up for an iMatch subscription, which is a cloud back-up service for music that costs $25/year, to listen ad-free. ITunes Radio will feature a "buy" button hooked up to iTunes, personalized radio stations, and unlimited skips.

Will it work? Seeing as how Apple has an ecosystem to fall back on (and plenty to sell), iTunes Radio has plenty of advantages on its side. All three major music labels have signed on, and Apple reportedly negotiated the terms of its advertising payouts to copyright holders in its favor, bypassing the "pureplay" license that has hampered Pandora.

Background: Unveiled during its developer conference, Google's service is mostly notable for beating Apple to the punch.

Specs: $9.99 per month for streaming access to "millions" of songs, plus a radio service in the same vein as Pandora, which allows unlimited skips.

Is it working? So far, it's received favorable reviews, but it's early yet. The service arrives on iOS soon, and though the Web app isn't quite as elegant as anything Apple has done, it's got enough features to keep users interested.

Background: Since it launched in 2011, Spotify has been gunning to become the industry leader, though it lags behind Pandora in terms of users--24 million with 6 million subscribers versus Pandora's 70.8 million users.

Is it working?: No. The company has yet to turn a profit, though Goldman Sachs says it's worth $3 billion and closed a $100 million funding round late last year.

Background: The "personalized radio" has an enviable user base--70.8 million active users as of May 2013--but not so enviable legal woes and royalty concerns.

Specs: Pandora offers a free ad-supported version, though its ads aren't great at targeting users, and an upgraded ad-free service for $3.99 per month or $36 a year. The company plans to expand to game consoles, including the PlayStation, and TV via HTML5.

Is it working? Definitely not. Despite going public in 2011, royalties and bandwidth are crippling its bottom line growth, though Pandora pays the lowest royalty rate in the industry ($0.12 per 100 songs versus $0.35 per 100 songs by Spotify).

Background: Rdio launched in 2010 and is available worldwide. Last week, CEO Drew Lerner stepped down.

Specs: Rdio is known for built-in music discovery and offers three types of monthly subscriptions--Web ($4.99), unlimited Web & mobile ($9.99), and unlimited family ($17.99). "Heavy Rotation" selects music based on what you've been listening to and who you follow, while "Collections" houses playlists in an easy-to-search tab.

Is it working? It's hard to tell, but the executive shake-up doesn't inspire confidence. In an interview with Bloomberg, Lerner said "momentum from last year has been tremendous," but declined to give specific figures.

Background: From the makers of Turntable.fm comes Piki, a Pandora-style radio app that serves up songs hand-picked by friends. Launched in December last year, it bills itself as a "music discovery application" that can be used with Spotify.

Specs: Free on mobile and desktop, Piki is super social--you can dedicate, share, and build playlists with friends--and has no listening limit. An Android app is due sometime this summer.

Background: In early 2011, Grooveshark's mobile app was pulled by Google and Apple, hampering any potential on mobile. After halving its staff to around 60 and enduring lawsuits from all four major record labels, the start-up is just beginning to regain its footing.

Specs: Grooveshark's redesigned free Web app focuses more on recommendations and social profiles. Drag-and-drop is possible, ads are all but nonexistent, and listeners can build playlists from previously streamed tracks. A premium, no-ads version goes for $9 per month or $90 per year.

Is it working? Not really. Co-founder and CEO Sam Tarantinotold Mashable he's broke and is trying to lower his rent. Grooveshark's user numbers are back around 30 million and its HTML5 player now has 3 million monthly users, with 200,000 new users joining every month.

Background: The New York City-based start-up has received its share of press, but has struggled to scale in a meaningful way.

Specs: Songza's free "Music Concierge" service recommends playlists by mood, which is a potential differentiator in a crowded market.

Is it working? Not yet. The company raised a $1.5 million convertible note from some notable investors late last year, and 2 million new users joined last summer. But it still hasn't said how it plans to monetize nor has it figured out a way to add users. The Associated Press reports Songza racked up 2 million listeners in May last year versus 1.2 billion on Pandora's website.